Conotoxins are peptides from venomous marine gastropods belonging to the Conus genus (500 species) that are common in tropical and sub-tropical waters. Venom is comprised of mostly small, highly constrained novel bioactive peptides, which act selectively at a number of sites, including sodium and calcium channels and nicotinic acetylcholine receptors. In this project we intend to use the state of the art mass spectrometric methods to identify conotoxins which are difficult to analyze because of their multiple di-sulphide bridges. New strategies for characterization of the disulfide-bridged pattern will be developed. Mapping of the peptides will be performed by capillary LC/ES/MS. According to the type of structural information needed for their identification, the peptides will then be analyzed by different MS techniques such as MALDI PSD MS, LSIMS MS/MS at high energy CID or LC/ES-MS/MS at low energy CID. Confirmation of the structure will be provided by synthesis of the peptides and different selective folding experiments for proving the disulphide connectitivities. The analytical work needed for the characterization of these very important toxins should not be underestimated and is essential for the development of conotoxins as strategic reagents for the pharmacological research.